Here's how ridiculously difficult it was to film 'Birdman' in 30 days

It won a total of four Oscars including best picture and best director.

The film, about a washed-up actor Riggan Thomson (Keaton) gearing up for a Broadway debut, underwent a rigorous schedule.

Shot in just 30 days in the spring of 2013 at the St. James Theatre in New York City's theater district, director Alejandro González Iñárritu insisted the film be made to appear as one continuous shot.

The St. James Theatre off W. 44th street in New York City. Google Maps

The camera work comes from Oscar-winning cinematographer Emmanuel Lubezki who worked on "Gravity." Try to spot a cut in the film and you'll maybe notice one. The film plays straight through pretty seamlessly.

During a panel for the movie at New York Comic Con in October, host Chris Hardwick described what it was like watching the film:

"There are these really long scenes where the camera will follow one character into a room and then something sort of weird and special effect-y happens and then someone else will come in and it will follow that character out. Meanwhile, there's stuff going on along the way to the next destination to a whole other area of the building and then there's something else completely in progress that is being orchestrated at the same time."

Keaton described the difficulty of prepping for the film to the magazine for its October 17 issue.

"Everybody showed up every morning frightened," Keaton told EW. "The crew too. I think we were all thinking, I don't want to be the guy who lets everybody down."

To give you an idea of how stressful it could be on set, the cast, crew, and camera team had to be readily in sync.

Here's how EW describes what one mistake would cost them on set.

"Anything—a misremembered line, an extra step taken, a camera operator stumbling on a stair or veering off course or out of focus—could blow a take, rendering the first several minutes unusable even if they had been perfect."

"You had to be word-perfect, you had to be off script, and you literally had to count your paces down to the number of steps you needed to take before turning a corner," Keaton told EW.

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"Everyone would apologize perfunctorily if they messed up ... mostly because we were aware of how hard it was on the camera operators," Keaton added. "And the camera operators didn't want to screw up because of us."

Norton didn't want to speak much about the making of the film at NYCC, wanting the film to instead speak for itself.

"I'm sure film schools will be deconstructing how a lot of it was done for a long time to come because it is really remarkable," said Norton. "I think suffice to say it was a level of planning you rarely see on a film. I thought it was wonderful because you rarely get that kind of rehearsal period on a film and you rarely get to work that intimately with the entire camera crew. It was all great. It has its challenges but it's a lot more fun actually than on a day-t0-day basis."

"It's amazing what he [Lubezki] pulled off as a cinematographer in this film," Norton added. "I think it's every bit as amazing as what he did in 'Gravity,' and yet in a totally different type of story and context."